Wrong. If I'm WVR with someone, I don't care what their RCS is, because I'm looking at them with my eyes.
OK, suppose they meant BVR and my RCS increased when I push the pickle button to launch a missile. Let's talk about what that actually means:
1) I've already seen him, created a launch quality que, and am shooting at him
2) So my RCS increases when the door opens, a missile pops out, he gets a lock on me. Then the missile goes away, the door closes, and depending on my range and flow, I either leave or ensure merge cleanup and watch his "Mighty Dragon" die. But as soon as my door closes...can his radar maintain the lock? Maybe...maybe not.
Suppose I'm not using an AMRAAM but an AIM-9 instead and that's why my missile is hanging out in the windstream. I'm probably not doing that at range, so I revert to my comment about being WVR...it doesn't matter what my RCS is because we're staring at each other across the circle.
I hate it when people who don't know about things talk as if they do. I hate it a lot. Maybe I'm doing it right now but don't realize it. Whatever.
edit to add paragraph about AIM-9.